• Progress in Medical Physics
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• v.15 no.3
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• pp.161-166
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• 2004

A simplistic quality assurance (QA) method was designed for a Linac built-in enhanced dynamic wedge (EDW), which can be utilized to make wedged beam distributions. For the purpose of implementing the EDW symmetry QA, a film dosimetry system, low speedy dosimetry film, film densitometer and 3D RTP system were used, and the films irradiated by means of a 60$^{\circ}$ Reversed wedge pair (REWP) method. The profiles were then analyzed in terms of their symmetries, including partial treatment, which is the case of stopping it abruptly during EDW irradiation, and the measured and calculated values compared using the Cad Plan Golden Segmented Treatment Table (Golden STT). The result of this experiment was in good agreement, within 1 %, of the 'reversed wedge pair counterbalance effect'. For the QA of the effective wedge factor (EWF), the authors measured EWFs in relation to the 10$^{\circ}$, 15$^{\circ}$, 20$^{\circ}$, 25$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$ EDW, which were compared with the calculated values using the correction factor derived from the Golden STT and the log files produced automatically during the process of EDW irradiation. By means of this method it was capable of check up the safety of effective wedge factor without any other dosimetry system. The EDW QA was able to be completed within 1 hour from irradiation to analysis as a consequence of the simplified QA procedure, with maximized effectiveness. Unlike the metal wedge system, the EDW system was heavily dependent on the dose rates and jaw movements; therefore, its features could potentially cause inaccuracy. The frequent simplistic QA for the EDW is essential, and could secure against the flaw of dynamic treatment that uses the EDW.

• Pediatric Infection and Vaccine
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• v.17 no.2
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• pp.156-168
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• 2010

Purpose : To compare immunogenicity and reactogenicity of a combined diphtheria-tetanus-acellular pertussis-inactivated poliovirus vaccine (DTPa-IPV, $Infanrix^{TM}$ IPV, GlaxoSmithKline Biologicals) with co-administration of commercially available DTPa and IPV vaccines at separate injection sites (DTPa+IPV). Methods : A total of 458 infants aged 8-12 weeks were randomized to receive three-ose primary vaccination at 2, 4 and 6 months with DTPa-IPV or DTPa+IPV. Blood samples were collected pre and post vaccination for measurement of immune responses. Reactogenicity was assessed following each dose using diary cards. Results : One month post-dose 3, seroprotection rates for anti-diphtheria, anti-tetanus and anti-poliovirus types 1, 2 and 3 were ${\geq}99.5%$ and vaccine response rates to pertussis antigens were at least 98.6% in both DTPa-IPV and DTPa + IPV groups. Non-inferiority between the groups was demonstrated based on pre-defined statistical criteria. Incidences of both local and systemic symptoms were within the same range across both groups with grade 3 symptoms reported following no more than 4.3% of DTPa-IPV doses and 4.5% of DTPa + IPV doses. Two serious adverse events (both pyrexia) after DTPa-IPV administration were considered vaccine-related. Both infants recovered fully. Conclusion : Combined DTPa-IPV vaccine was immunogenic and well tolerated when used as a three-dose primary vaccination course in Korean infants. DTPa-IPV could be incorporated into the Korean vaccination schedule, reducing the number of injections required to complete primary immunization.

• Journal of the Ergonomics Society of Korea
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• v.36 no.3
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• pp.183-196
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• 2017

Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. Basically, the difference between univariate and multivariate analysis is that univariate analysis deals with one predictor variable at a time, whereas multivariate analysis deals with multiple predictor variables combined in a predetermined manner. The univariate analysis could show how each variable is associated with epicondyle pain. This may allow more appropriate weighting factors to be determined and therefore improve the performance of the EEM.

• Progress in Medical Physics
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• v.26 no.1
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• pp.42-51
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• 2015

In proton therapy, verification of proton dose distribution is important to treat cancer precisely and to enhance patients' safety. To verify proton dose distribution, in a previous study, our team incorporated a vertically-aligned one-dimensional array detection system. We measured 2D prompt-gamma distribution moving the developed detection system in the longitudinal direction and verified similarity between 2D prompt-gamma distribution and 2D proton dose distribution. In the present, we have developed two-dimension prompt-gamma measurement system consisted of a 2D parallel-hole collimator, 2D array-type NaI(Tl) scintillators, and multi-anode PMT (MA-PMT) to measure 2D prompt-gamma distribution in real time. The developed measurement system was tested with $^{22}Na$ (0.511 and 1.275 MeV) and $^{137}Cs$ (0.662 MeV) gamma sources, and the energy resolutions of 0.511, 0.662 and 1.275 MeV were $10.9%{\pm}0.23p%$, $9.8%{\pm}0.18p%$ and $6.4%{\pm}0.24p%$, respectively. Further, the energy resolution of the high gamma energy (3.416 MeV) of double escape peak from Am-Be source was $11.4%{\pm}3.6p%$. To estimate the performance of the developed measurement system, we measured 2D prompt-gamma distribution generated by PMMA phantom irradiated with 45 MeV proton beam of 0.5 nA. As a result of comparing a EBT film result, 2D prompt-gamma distribution measured for $9{\times}10^9$ protons is similar to 2D proton dose distribution. In addition, the 45 MeV estimated beam range by profile distribution of 2D prompt gamma distribution was $17.0{\pm}0.4mm$ and was intimately related with the proton beam range of 17.4 mm.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.1
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• pp.7-12
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• 2006

Purpose: This is for the purpose to help the bill related to technologists be systematic and unitary by carefully analyzing a legislation, an enforcement ordinance, and enforcement regulations in the connection with the radiological worker and the radiation workers from the law and regulations related to technologists. Materials and Methods: Concerning technologists, a legislation, an enforcement ordinance, and enforcement regulations for a sort of medical technician, regarding the radiological worker, the rules of diagnosis radiation equipment safety management, and concerning the radiation workers, atomic energy law, an enforcement ordinance and enforcement regulations were gathered, compared with one another, and analyzed. Results: Among technologists, in the case of working in the department of diagnosis radiation, the title 'Radiological Worker' is used by the Medical Service Law, and in the case of working in the department of radiation tumors or the one of nucleus medicine, the title 'Radiation Workers' is used by the Atomic Energy Law. Conclusion: Besides the technical term that is used by characteristic tasks, unification of the terms that can be used in common is necessary for sure. And when a legislation, an enforcement ordinance, enforcement regulations, and notification, things like that in the radiation field are amended, certainly they should be done by mutual agreement through negotiation between the organization related to radiation and the governmental organization.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.633-638
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• 2017

The amount of radioactive waste has been rapidly increased with development of radiation treatment in medical field. Recently, it has been a common practice to use I-131 for thyroid cancer, F-18 for PET/CT and Tc-99m for diagnosis of nuclear medicine. All the wastes concerned have been disposed of by means of the self-disposal method, for example incineration, after storage enough to decay less than clearance level. IAEA proposed criteria for clearance level of waste which depends on the individual ($10{\mu}Sv/y$) and collective dose (1 man-Sv/y), and concentration of each nuclide (IAEA Safety Series No 111-P-1.1, 1992 and IAEA RS-G-1.7, 2004). In this study, specific radioactivity of radioactive waste contaminated with Re-186 was measured to confirm whether it meets the clearance level. Re-186 has long half life of 3.8 days relatively and emits beta and gamma radiation, therefore it can be applied in treatment and imaging purposes. The specific radioactivity of contaminated gloves weared by radiation workers was measured by MCA(Multi-channel Analyzer) which was calibrated by reference materials in accordance with the measuring procedure. As a result, comparison evaluation of decay storage period between the half-life which was calculated by attenuation curve based on real measurement and physical half-life was considered, and it is showed that the physical half-life is longer than induced half-life. Therefore, the storage period of radioactive waste for self-disposal may be curtailed in case of application of induced half-life. The result of this study will be proposed as ISO standard.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.895-908
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• 2018

As modern science is developed and advanced, examination and number of times using radiation are increasing daily. General diagnostic X-ray generator is installed on stationary form, But X-ray generator was developed because patient who is in the intensive care unit, operation room, emergency room can not move to general x-ray room. What we examine patient by x-ray generator is certainly necessary, So patient exposure is inevitable. but reducing radiation exposure is highly important matter about radiation technology, guardian, patient in the same hospital room, nurse etc. For this reason, rule regarding safety control of diagnostic x-ray generator revised for radiation worker, patient and protector proclaim that mobile diagnostic x-ray shield must placed in case of examine different location excluding operation room, emergency room, intensive care unit. But, radiogical technologist is having a lot of difficulties to examine with mobile x-ray generator, diagnostic x-ray shield partition, image plate and lead apron. So, when we use x-ray generator, we manufacture shield tools can be attached to the mobile x-ray generator On behalf of x-ray shield partition and conduct analysis and in comparison to part of body and distribution of dose rate and find way to reduce radiation exposure through distribution of dose rate of patient within the radiogical technologist, medical team. Mobile x-ray generator aimed at SHIMADZU inc. R-20, We manufactured equipment for shielding x-ray scattered x-ray by installing shielding wall from side to side based on support beam on the mobile x-ray generator. Shielding wall when moving can be folded and designed to expand when examine. Experiment measured five times in each by an angle for dose rate of eyes, thyroid, breast, abdomen and gonad on exposure condition of upper and lower extremity, chest, abdomen which is examined many times by mobile x-ray generator. We used dosimeter RSM-100 made by IJRAD and measured a horizontal dose rate by body part. The result of an experiment, shielding decreasing rate of the front and the rear showed 77 ~ 98.7%. Therefore using self-production shielding wall reduce scattered x-ray occurrence rate and confirm can decrease exposure dose consequently. Therefore, through this study, reduction result which is used shielding wall of self-production will be a role of shielding optimization and it could be answer about reduction of medical exposure recommended by ICRP 103.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1658-1670
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• 2021

Objective: To assess the two-year treatment outcomes of chemoembolization with drug-eluting embolics (DEE) for nodular hepatocellular carcinoma (HCC). Materials and Methods: This study was a prospective, multicenter, registry-based, single-arm trial conducted at five university hospitals in Korea. Patients were recruited between May 2011 and April 2013, with a target population of 200. A DC Bead loaded with doxorubicin was used as the DEE agent. Patients were followed up for two years. Per-patient and per-lesion tumor response analysis, per-patient overall survival (OS) and progression-free survival (PFS) analysis, and per-lesion tumor control analysis were performed. Results: The final study population included 152 patients, with 207 target lesions for the per-lesion analysis. At one-month, six-month, one-year, and two-year per-patient assessments, complete response (CR) rates were 40.1%, 43.0%, 33.3%, and 19.6%, respectively. The objective response (OR) rates were 91.4%, 55.4%, 35.1%, and 19.6%, respectively. The cumulative two-year OS rate was 79.7%. The cumulative two-year PFS rate was 22.4% and the median survival was 9.3 months. In multivariable analysis, the Child-Pugh score (p = 0.019) was an independent predictor of OS, and tumor multiplicity (p < 0.001), tumor size (p = 0.020), and Child-Pugh score (p = 0.006) were independent predictors of PFS. In per-lesion analysis, one-month, six-month, one-year and two-year CR rates were 57.5%, 58.5%, 45.2%, and 33.3%, respectively, and the OR rates were 84.1%, 65.2%, 46.6%, and 33.3%, respectively. The cumulative two-year per-lesion tumor control rate was 36.2%, and the median time was 14.1 months. The Child-Pugh score (p < 0.001) was the only independent predictor of tumor control. Serious adverse events were reported in 11 patients (7.2%). Conclusion: DEE chemoembolization for nodular HCCs in the Korean population showed acceptable survival, tumor response, and safety profiles after a two-year follow-up. Good liver function (Child-Pugh score A5) was a key predictor of per-patient OS, PFS, and per-lesion tumor control.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.1-10
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• 2002

High energy photon beams from medical linear accelerators produce large scattered radiation by various components of the treatment head, collimator and walls or objects in the treatment room including the patient. These scattered radiation do not provide therapeutic dose and are considered a hazard from the radiation safety perspective. Scattered dose of therapeutic high energy radiation beams are contributed significant unwanted dose to the patient. ICRP take the position that a dose of 500mGy may cause abortion at any stage of pregnancy and that radiation detriment to the fetus includes risk of mental retardation with a possible threshold in the dose response relationship around 100 mGy for the gestational period. The ICRP principle of as low as reasonably achievable (ALARA) was recommended for protection of occupation upon the linear no-threshold dose response hypothesis for cancer induction. We suggest this ALARA principle be applied to the fetus and testicle in therapeutic treatment. Radiation dose outside a photon treatment filed is mostly due to scattered photons. This scattered dose is a function of the distance from the beam edge, treatment geometry, primary photon energy, and depth in the patient. The need for effective shielding of the fetus and testicle is reinforced when young patients ate treated with external beam radiation therapy and then shielding designed to reduce the scattered photon dose to normal organs have to considered. Irradiation was performed in phantom using high energy photon beams produced by a Varian 2100C/D medical linear accelerator (Varian Oncology Systems, Palo Alto, CA) located at the Yonsei Cancer Center. The composite phantom used was comprised of a commercially available anthropomorphic Rando phantom (Phantom Laboratory Inc., Salem, YN) and a rectangular solid polystyrene phantom of dimensions $30cm{\times}30cm{\times}20cm$. the anthropomorphic Rando phantom represents an average man made from tissue equivalent materials that is transected into transverse 36 slices of 2.5cm thickness. Photon dose was measured using a Capintec PR-06C ionization chamber with Capintec 192 electrometer (Capintec Inc., Ramsey, NJ), TLD( VICTOREEN 5000. LiF) and film dosimetry V-Omat, Kodak). In case of fetus, the dosimeter was placed at a depth of loom in this phantom at 100cm source to axis distance and located centrally 15cm from the inferior edge of the $30cm{\times}30cm^2$ x-ray beam irradiating the Rando phantom chest wall. A acryl bridge of size $40cm{\times}40cm^2$ and a clear space of about 20 cm was fabricated and placed on top of the rectangular polystyrene phantom representing the abdomen of the patient. The leaf pot for testicle shielding was made as various shape, sizes, thickness and supporting stand. The scattered photon with and without shielding were measured at the representative position of the fetus and testicle. Measurement of radiation scattered dose outside fields and critical organs, like fetus position and testicle region, from chest or pelvic irradiation by large fie]d of high energy radiation beam was performed using an ionization chamber and film dosimetry. The scattered doses outside field were measured 5 - 10% of maximum doses in fields and exponentially decrease from field margins. The scattered photon dose received the fetus and testicle from thorax field irradiation was measured about 1 mGy/Gy of photon treatment dose. Shielding construction to reduce this scattered dose was investigated using lead sheet and blocks. Lead pot shield for testicle reduced the scatter dose under 10 mGy when photon beam of 60 Gy was irradiated in abdomen region. The scattered photon dose is reduced when the lead shield was used while the no significant reduction of scattered photon dose was observed and 2-3 mm lead sheets refuted the skin dose under 80% and almost electron contamination. The results indicate that it was possible to improve shielding to reduce scattered photon for fetus and testicle when a young patients were treated with a high energy photon beam.

• Korean Journal of Cleft Lip And Palate
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• v.9 no.2
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• pp.85-92
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• 2006

Korean Cleft Lip and Palate Association (KCLPA) was founded in 1996. The first overseas charity operation was in Karachi, Pakistan, 2002 and our association has visited fourteen times in six countries for the free cleft surgery: Pakistan, Egypt, Kenya, Morocco, Jordan and Vietnam. The cumulated number of operated patients reaches to 280. Before our association, many Korean oral and maxillofacial surgeons have performed charity operations individually since 1964. It was started from Vietnam but the activity is now carried on in Africa, middle-east Asia, south-east Asia, China, and Korea as an official team. LG electronics, a Korean company helped to propagate our team's activity to middle-east Asia to Africa. This paper is a report concerning about the results of our association's charity activities especially in Kenya, east Africa. We provided free cleft surgery for 30 patients in 2004 and 27 patients in 2005, in Nairobi. As the blood test for HIV of the cleft patients was not allowed before and during surgery, our surgeons and nurses were cautious about every movement during the surgeries. Thus the operation time for each patient was longer than any other time. The attitude of the local hospital and the doctors seemed to be accustomed to this situation. They helped us in case of needle injuries. Safety of medical staff and patients is more important than the number of the patients operated in charity operation. This belief should be approached being parallel and multidisciplinary as an international cooperation, focusing on international funding for medical support and continuous education for local doctors who are willing to devote to their people.